Various display systems and display methods have been used over the years to generate images. For example, both front and rear projection systems are used today to display images. Such display systems may employ image devices, such as cathode ray tubes (CRTs), liquid crystal displays (LCDs), or electrically-addressed emissive displays, e.g. plasma displays. The display systems further may incorporate a passive display screen or an active display screen.
The marketability of each display system depends on numerous factors, including, but not limited to, image quality, image resolution, image brightness, display size, cost, weight, design, etc. A consumer may choose a display system based on any one factor, or any combination of these factors. For example, the level of shading or half-toning may be important to a consumer when the display system is primarily used to display graphical or photographic images. Edge definition and contrast also may be important. A consumer may want a display system having both high quality shading and high quality edge definition. However, until now, the cost of display systems that attempt to provide both high quality half-toning and high quality edge definition has been prohibitive.
A system for enhancing the quality of an image on a screen is provided. The system typically includes an illumination source configured to produce light and direct such light along an optical path, and a variable focus device disposed in the optical path and configured to sequentially alter incident light to enhance the quality of the image on the screen.